This invention relates to certain imidazopyridines and related azacyclic derivatives which when appropriately substituted are selective modulators of Bradykinin B2 receptors. This invention also relates to pharmaceutical compositions comprising such compounds. It further relates to the use of such compounds in treating a variety of central and peripheral disorders. Additionally, compounds of this invention are useful as positive controls in assays for BK-2 receptor activity and when appropriately labeled as probes for the localization of BK-2 receptors in tissue sections.
Bradykinin (BK), a nonapeptide, and the closely related decapeptide kallidin (Lys-BK), are produced by proteolytic cleavage of high molecular weight kininogen by plasma kallikreins. The effects of bradykinin and kallidin are mediated by specific seven transmembrane G-protein coupled receptors.
The existence of two bradykinin receptor subtypes has been unequivocally confirmed within the last six years. The expression and cloning of a rat bradykinin receptor, now known to be a BK-2 receptor, was first reported followed by the cloning and pharmacological characterization of a human BK-2 receptor. The expression and cloning of a human bradykinin (B1) receptor has also been described.
Both BK and kallidin activate the B2 receptor while only kallidin is active at the B1 receptor. However, both compounds are rapidly cleaved to produce B1 receptor agonists, and then further degraded by kinases to produce inactive peptides. The instability of BK and kallidin suggests that these peptides act locally. Both receptors are expressed in a number of peripheral tissues as well as in the Central Nervous System (CNS).
The B2 receptor is expressed constitutively in a variety of tissues and accounts for the majority of the acute pharmacological effects of bradykinin. The B1 receptor is inducibly expressed and appears to act predominantly in pathophysiological conditions. The BK-1 receptor has been especially implicated in persistent hyperalgesia and chronic inflammation.
Bradykinin is an effector of a number of inflammatory responses including bronchoconstriction, plasma extravasation, release of prostaglandins/leukotrienes, smooth muscle contraction/relaxation and nociception. Bradykinin and the related peptide kallidin have been implicated in a number of disease conditions, including but not limited to pain, rhinitis, anaphylaxis, inflammatory bowel disease, vascular permeability, algesia, vasodilataion, inflammatory response, hypotension associated with sepsis, bronchopulmonary disorders including asthma, and increased cell proliferation. Antagonists of the BK-2 receptor are useful in treating these conditions. Additionally bradykinin has been implicated in increased glucose uptake, and decreased blood glucose concentration. Therefore agonists of the BK-2 receptor may be useful in the treatment of Type II diabetes. An increased permeability of the blood-brain barrier due to bradykinin has also been reported. Thus, agonists of the BK-2 receptor may also be used to increase the brain levels of pharmaceutical compounds used to treat central nervous system disorders when administered with these compounds. Therefore, compounds that modulate the bradykinin B2 (BK-2) receptor as agonists or antagonists would have considerable therapeutic benefit.
A number of tissues and cultured cell lines have been assessed for the presence of bradykinin receptors using radiolabeled bradykinin or a radiolabeled bradykinin analogue as a probe (See Hall, Gen. Pharma., 1997, 28: 1-6, for a compilation of such studies.). Although bradykinin and its analogues exhibit high affinity for bradykinin receptors there are some difficulties in using these ligands as receptor localization probes. Bradykinin binds to both BK-1 and BK-2 receptors and therefore cannot be used to distinguish receptor subtypes. Also bradykinin and many of its peptide analogues are susceptible to rapid degradation by kininases, leading to experimental difficulties. Nonpeptidic ligands are not susceptible to kininase activity. Therefore, small molecules that bind with high affinity and high selectivity to BK-2 receptors are especially desirable tools for BK-2 localization studies.
Various compounds have been prepared as modulators of BK-2 receptors. The following disclose non-peptidic compounds that modulate Bradykinin B2 receptors: EP-622361-A1, WO 98/42672, WO 97/41104, WO 97/28153, WO 96/13485, EP-596406-A1, EP-835659-A1, EP-808-838-A1, EP-796-848-A1, WO 98/03503, WO 97/24349, U.S. Pat. No. 5,438,064, U.S. Pat. No. 5,216,165, U.S. Pat. No. 5,212,182, WO 97/30048, EP 790239-A1, U.S. Pat. No. 5,510,380, U.S. Pat. No. 5,817,756.
The compounds most closely related structurally to the present invention are a series of imidazopyridine ureas described in JP 95-350957 as cholesterol acyltransferase inhibitors. None of the compounds from JP 95-350957 are described as bradykinin antagonists.
This invention provides novel compounds of Formula I (shown below) and pharmaceutical compositions comprising compounds of Formula I. Such compounds exhibit high selectivity for bradykinin B2 receptors. Compounds of Formula I also bind with high affinity to these receptors.
The invention further provides methods of treating patients suffering from certain inflammatory disorders and other conditions mediated by bradykinin. The invention also provides methods of treating patients (humans and non-humans) suffering from conditions in which agonism of the BK-2 receptor may prove beneficial. Treatment of humans, domesticated companion animals (pets) or livestock animals suffering such conditions with an effective amount of a compound of the invention is contemplated by the invention.
In a separate aspect, the invention provides methods of using compounds of this invention as positive controls in assays for BK-2 receptor activity and using appropriately labeled compounds of the invention as probes for the localization of BK-2 receptors in tissue sections.
A broad aspect of the invention is directed to compounds of Formula I: 
or the pharmaceutically acceptable non-toxic salts thereof wherein: 
represents a nitrogen-containing ring system, in which not more than two of A, B, C, or D represent nitrogen and remaining ring members are carbon, and which nitrogen-containing ring system is optionally substituted with up to four substituents independently selected from:
(i) hydroxyl, halogen, trifluoromethyl, C1-C6 alkyl, trifluoromethoxy, C1-C6 alkoxy, aminomethyl, mono or di(C1-C6)alkylamino, mono or dialkylaminomethyl (wherein each alkyl is independently lower C1-C6 alkyl),
(ii) C1-C6alkoxyNR7R8, NR7R8, NR7COR8, CONR7R8, wherein R7 and R8 are same or different and represent hydrogen, or straight or branched chain lower alkyl, or R7 and R8 are joined together to form a 5, 6, or 7 membered heterocyclic ring, which is optionally substituted with halogen, nitro, trifluoromethyl, cyano, hydroxyl, C1-C6 alkyl, amino, mono or di(C1-C6)alkylamino, or C1-C6 alkoxy, and
(iii) O(CH2)nCO2RA (where n=1,2,3, or 4), CORA, and CO2RA wherein RA represents hydrogen, or straight or branched chain lower alkyl;
R1 is arylalkyl, heteroarylalkyl, or allyl each of which is optionally substituted directly or through a O(CH2)n linker (where n=1,2, 3 or 4) with up to three substituents independently selected from:
(i) halogen (with the proviso that R1 may not be 3-Fluorobenzyl), nitro, trifluoromethyl, trifluoromethoxy, cyano, hydroxyl, C1-C6 alkyl, amino, C1-C6 alkoxy, aminomethyl, mono or di(C1-C6)alkylamino, mono or dialkylaminomethyl (wherein each alkyl is independently lower C1-C6 alkyl),
(ii) C1-C6alkoxyNR7xe2x80x2R8xe2x80x2, NR7xe2x80x2R8xe2x80x2, NR7xe2x80x2COR8xe2x80x2, CONR7xe2x80x2R8xe2x80x2, wherein R7xe2x80x2 and R8xe2x80x2 are the same or different and represent hydrogen, or straight or branched chain lower alkyl, or R7xe2x80x2 and R8xe2x80x2 are joined together to form a 5, 6, or 7 membered heterocyclic ring, which is optionally substituted with halogen, nitro, trifluoromethyl, cyano, hydroxyl, C1-C6 alkyl, amino, mono or di(C1-C6)alkylamino, or C1-C6 alkoxy,
(iii) O(CH2)nCO2RAxe2x80x2 (where n=1 ,2,3, or 4), CORAxe2x80x2, CO2RAxe2x80x2, wherein RAxe2x80x2 represents hydrogen, or straight or branched chain lower alkyl,
(iv) SO2RAxe2x80x2, NHSO2RAxe2x80x2, SO2NHRAxe2x80x2, SO2NHCORAxe2x80x2, CONHSO2RAxe2x80x2, wherein RAxe2x80x2 is as defined above,
(v) tetrazole, triazole, imidazole, thiazole, oxazole, thiophene, naphthyl, and pyridyl (each of which may be optionally substituted with halogen, hydroxyl, amino, nitro, cyano, C1-C6 alkyl, and C1-C6 alkoxy);
R3 represents straight or branched chain lower alkyl;
R4 represents halogen or trifluoromethyl;
R5, R6, and R6xe2x80x2 are the same or different and represent
(i)hydrogen, trifluoromethyl, trifluoromethoxy, nitro, cyano, lower alkyl, halogen, aminomethyl, mono or dialkylamino, mono or dialkylaminomethyl, wherein each alkyl is independently lower alkyl, or C1-C6alkoxyaminoalkyl where the amino is mono or disubstituted with straight or branched chain lower alkyl;
(ii) C1-C6 alkoxy (with the proviso that R5, R6, or R6xe2x80x2 may not be C1-C6 alkoxy when located ortho to Y) which is optionally substituted with
(a) C1-C6 alkoxy, C1-C6 alkylthio, amino, hydroxy, halogen, haloalkyl, mono or di(C1-C6)alkylamino, morpholino, or thiomorpholino
(b)mono or di(C1-C10)alkylamino1, wherein said mono or di(C1-C10)alkylamino1, is substituted with aryl, arylalkyl, heteroarylalkyl, heteroarylalkyl, C3-C7 cycloalkyl, (C3-C7 cycloalkyl)C1-C4alkyl, C3-C7heterocycloalkyl, (C3-C7 cycloalkyl)C1-C4alkyl wherein each aryl, heteroaryl, cycloalkyl, or heterocycloalkyl group substituting said mono or di(C1-C10)alkylamino1 is optionally substituted by alkyl, oxo, halogen, hydroxyl, trifluoromethyl, trifluromethoxy, or alkoxy;
R4 and R5 are joined to form a 5, 6, or 7 membered carbocyclic or heterocyclic aromatic ring which is optionally substituted with up to four substitutents selected from:
(i) halogen, nitro, trifluoromethyl, cyano, hydroxyl, C1-C6 alkyl, amino, C1-C6 alkoxy, aminomethyl, mono or dialkylamino, mono or dialkylaminomethyl (wherein each alkyl is independently lower alkyl),
(ii)C1-C6alkoxyNR7xe2x80x3R8xe2x80x3, NR7xe2x80x3R8xe2x80x3, CONR7xe2x80x3R8xe2x80x3, NR7xe2x80x3COR8xe2x80x3, where R7xe2x80x3 and R8xe2x80x3 are the same or different and represent hydrogen or straight or branched chain lower alkyl, or R7xe2x80x3 and R8xe2x80x3 may be a 5, 6, or 7 membered heterocyclic ring, which is optionally substituted with halogen, nitro, trifluoromethyl, cyano, hydroxyl, lower alkyl, amino, mono or dialkylamino (wherein each alkyl is independently lower alkyl) or C1-C6 alkoxy,
(iii)O(CH2)nCO2RAxe2x80x3 where n=1,2,3,4, CORAxe2x80x3, or CO2RAxe2x80x3 where RAxe2x80x3 represents hydrogen or straight or branched chain lower alkyl having 1-6 carbon atoms
and R6 and R6xe2x80x2 are as defined above; and
Y represents a bond or CH2, when Y=CH2 it may be mono or disubstituted with a straight or branched chain lower alkyl, or straight or branched chain lower alkoxy having 1-6 carbon atoms.
The novel compounds encompassed by the instant invention can be described by the following general formula Ia: 
or the pharmaceutically acceptable non-toxic salts thereof wherein: 
is as defined above for Formula I, R1, R3, and Y are as defined above;
R4 represents hydrogen, halogen or trifluoromethyl; and
R5, R6, and R6xe2x80x2 are the same or different and represent hydrogen, trifluoromethyl, trifluoromethoxy, nitro, cyano, lower alkyl having 1-6 carbon atoms, C1-C6 alkoxy (with the proviso that R5, R6, and R6xe2x80x2 may not be C1-C6 alkoxy when located ortho to Y in Formula Ia), halogen, aminomethyl, mono or dialkylaminomethyl (where each alkyl is independently lower (C1-C6) alkyl), and
C1-C6 alkoxyaminoalkyl where the amino is mono or disubstituted with straight or branched chain lower alkyl having 1-6 carbon atoms.
Other novel compounds of Formula I may be comprised of compounds of general Formula Ib: 
or the pharmaceutically acceptable non-toxic salts thereof wherein: 
is as defined above, and R1, R3, and Y are as defined above;
R4 and R5 form a 5, 6, or 7 membered carbocyclic or heterocyclic aromatic ring which is optionally substituted with up to four substituents independently selected from:
halogen, nitro, trifluoromethyl, cyano, hydroxyl, C1-C6 alkyl, amino, C1-C6 alkoxy, aminomethyl,
mono or dialkylamino, mono or dialkylaminomethyl (wherein each alkyl is independently lower alkyl),
C1-C6alkoxyNR7xe2x80x3R8xe2x80x3, NR7xe2x80x3R8xe2x80x3, CONR7xe2x80x3R8xe2x80x3, NR7xe2x80x3COR8xe2x80x3,
where R7xe2x80x3 and R8xe2x80x3 are the same or different and represent hydrogen or straight or branched chain lower alkyl,
or R7xe2x80x3 and R8xe2x80x3 may be a 5, 6, or 7 membered heterocyclic ring, which is optionally substituted with halogen, nitro, trifluoromethyl, cyano, hydroxyl, lower alkyl, amino, mono or dialkylamino (wherein each alkyl is independently lower alkyl) or C1-C6 alkoxy,
O(CH2)nCO2RAxe2x80x3 where n=1,2,3,4, CORAxe2x80x3, or CO2RAxe2x80x3
where RAxe2x80x3 represents hydrogen or straight or branched chain lower alkyl having 1-6 carbon atoms
R6, and R6xe2x80x2 are the same or different and represent hydrogen, halogen, trifluoromethyl, trifluoromethoxy, nitro, cyano, lower alkyl, C1-C6 alkoxy (with the proviso that R6 or R6xe2x80x2 may not be C1-C6 alkoxy when located ortho to Y),
aminomethyl, mono or dialkylamino, mono or dialkylaminomethyl,
wherein each alkyl is independently a straight or branched chain lower alkyl, or C1-C6 alkoxyaminoalkyl where the amino is mono or disubstituted with straight or branched chain lower alkyl having 1-6 carbon atoms.
One preferred embodiment of the present invention encompasses compounds of Formula II and pharmaceutically acceptable salts thereof; 
wherein R1 and R3 are as defined above.
In a more preferred embodiment the invention encompasses compound of Formula II and the pharmaceutically acceptable salts thereof wherein R3 is isoamyl or n-pentyl, and R1 is as defined above.
Another preferred embodiment of the present invention encompasses compounds of Formula III and the pharmaceutically acceptable salts thereof; 
wherein R1 and R3 are as defined above.
In a more preferred embodiment the invention encompasses compound of Formula III and the pharmaceutically acceptable salts thereof wherein R3 is isoamyl or n-pentyl, and R1 is as defined above.
In another preferred embodiment, the present invention encompasses compounds of Formula IV 
wherein:
R1, and R3 are as defined above and R4 represents hydrogen, halogen or trifluoromethyl.
In a more preferred embodiment the invention encompasses compounds of Formula IV and the pharmaceutically acceptable salts thereof wherein R1 is as defined above, R3 is isoaamyl or n-pentyl, and R4 represents chlorine, bromine, or trifluoromethyl.
In certain situations, the compounds of Formula I may contain one or more asymmetric carbon atoms, so that the compounds can exist in different stereoisomeric forms. These compounds can be, for example, racemates or optically active forms. In these situations, the single enantiomers, i.e., optically active forms, can be obtained by asymmetric synthesis or by resolution of the racemates. Resolution of the racemates can be accomplished, for example, by conventional methods such as crystallization in the presence of a resolving agent, or chromatography, using, for example a chiral HPLC column.
Representative compounds of the present invention, which are encompassed by Formula I, include, but are not limited to the compounds described in the Examples and their pharmaceutically acceptable acid addition salts. In addition, if the compound of the invention is obtained as an acid addition salt, the free base can be obtained by basifying a solution of the acid salt. Conversely, if the product is a free base, an addition salt, particularly a pharmaceutically acceptable addition salt, may be produced by dissolving the free base in a suitable organic solvent and treating the solution with an acid, in accordance with conventional procedures for preparing acid addition salts from base compounds.
Non-toxic pharmaceutical salts include salts of acids such as hydrochloric, phosphoric, hydrobromic, sulfuric, sulfinic, formic, toluenesulfonic, methanesulfonic, nitric, benzoic, citric, tartaric, maleic, hydroiodic, alkanoic such as acetic, HOOCxe2x80x94(CH2)nxe2x80x94COOH where n is 0-4, and the like. Those skilled in the art will recognize a wide variety of non-toxic pharmaceutically acceptable addition salts.
The present invention also encompasses the acylated prodrugs of the compounds of Formula I. Those skilled in the art will recognize various synthetic methodologies which may be employed to prepare non-toxic pharmaceutically acceptable addition salts and acylated prodrugs of the compounds encompassed by Formula I.
When any variable occurs more than one time in any constituent or formula for a compound, its definition at each occurrence is independent of its definition at every other occurrence. Thus, for example, if a group is shown to be substituted with 0-2 R*, then said group may optionally be substituted with up to two R* groups and R* at each occurrence is selected independently from the definition of R*. Also, combinations of substituents and/or variables are permissible only if such combinations result in stable compounds.
The term xe2x80x9carylxe2x80x9d in the present invention means a monocyclic or bicyclic aromatic group having preferably 6 to 10 carbon atoms, such as, for example, phenyl or naphthyl.
By xe2x80x9carylalkylxe2x80x9d or xe2x80x9cheteroarylalkylxe2x80x9d in the present invention is meant a branched or straight-chain alkyl group having from 1 to about 6 carbon atoms and substituted on one of the carbon atoms by an optionally substituted aryl or heteroaryl ring, such as, for example, benzyl, phenethyl, methylpyridyl, ethylpyridyl, and the like.
By xe2x80x9calkylxe2x80x9d in the present invention is meant C1-C10 alkyl, i.e., straight or branched chain alkyl groups having 1-10 carbon atoms, preferably 1-6 carbon atoms (C1-C6 alkyl), such as, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, 2-pentyl, isopentyl, neopentyl, hexyl, 2-hexyl, 3-hexyl, and 3-methylpentyl. Preferred C1-C10 alkyl groups are methyl, ethyl, propyl, butyl, cyclopropyl or cyclopropylmethyl.
By xe2x80x9clower alkylxe2x80x9d in the present invention is meant C1-C6 alkyl, i.e., straight or branched chain alkyl groups having 1-6 carbon atoms.
By xe2x80x9calkoxyxe2x80x9d or xe2x80x9clower alkoxyxe2x80x9d in the present invention is meant C1-C6 alkoxy, i.e., straight or branched chain alkoxy groups having 1-6 carbon atoms, such as, for example, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, pentoxy, 2-pentyl, isopentoxy, neopentoxy, hexoxy, 2-hexoxy, 3-hexoxy, and 3-methylpentoxy.
By xe2x80x9chalogenxe2x80x9d in the present invention is meant fluorine, bromine, chlorine, and iodine.
By (hetero) cyclic ring is meant a ring that is either aliphatic or aromatic and optionally contains at least one hetero atom. Hetero atoms include nitrogen, sulfur, and oxygen. Examples of such (hetero) cyclic rings are cyclohexyl, cyclopentyl, piperidinyl, piperazinyl, pyrrolidinyl, morpholinyl, etc.
By heteroaryl (aromatic heterocycle) in the present invention is meant one or more aromatic ring systems of 5-, 6-, or 7-membered rings containing at least one and up to four hetero atoms selected from nitrogen, oxygen, or sulfur. Such heteroaryl groups include, for example, thienyl, furanyl, thiazolyl, imidazolyl, (is)oxazolyl, pyridyl, pyrimidinyl, imidazolyl, (iso)quinolinyl, naphthyridinyl, benzimidazolyl, and benzoxazolyl.
The structure of Formula I as shown in the specification and as used in the claims includes all possible tautomers and rotamers.
Selective agonists or antagonists of the bradykinin B2 receptor provide compounds useful in treatment of renal diseases, heart failure, hypertension, Meniere""s disease, vaginal inflammation and pain, peripheral circulatory disorders, climacteric disturbance, retinochoroidal circulatory disorders, myocardial ischemia, myocardial infarction, postmyocardial infarction syndrome, angina pectoris, restenosis after percutaneous transluminal coronary angioplasty, hepatitis, liver cirrhosis, pancreatitis, ileus, diabetes, diabetic complications, male infertility or glaucoma, for the increase of permeability of blood-brain barrier or blood-brain-tumor barrier, pain, asthma, rhinitis. These interactions result in the pharmacological activities of these compounds.
The invention also provides pharmaceutical composition comprising compounds of the invention.
The invention also provides packaged pharmaceutical compositions comprising pharmaceutical compositions of the invention in a container and instructions for using the composition to treat a patient in need thereof. In one embodiment, the instructions are for using the composition to treat a patient suffering from a physiological disorder associated with an excess of or insufficient amount of bradykinin. The patient may be suffering, for example, from renal disease, heart failure, hypertension, Meniere""s disease, vaginal inflammation and pain, peripheral circulatory disorders, climacteric disturbance, retinochoroidal circulatory disorders, myocardial ischemia, myocardial infarction, postmyocardial infarction syndrome, angina pectoris, restenosis after percutaneous transluminal coronary angioplasty, hepatitis, liver cirrhosis, pancreatitis, ileus, diabetes, diabetic complications, male infertility or glaucoma, asthma, rhinitis, brain cancer, or a brain tumor.
The invention further provides methods of treating patients in suffering from an inflammatory disorder with an amount of a compound of the invention sufficient to alter the symptoms of the inflammatory disorder. Inflammatory disorders that may be treated with a selective antagonist of the BK-2 receptor include restenosis after percutaneous transluminal coronary angioplasty, rhinitis, inflammation associated with brain trauma, stroke, sepsis, anaphylaxis, Meniere""s disease, pancreatitis, ileus, inflammatory bowel disease, and bronchopulmonary disorders including asthma. The invention also provides methods of treating patients suffering from pain with a pain-reducing amount of a compound of the invention. Painful conditions that may be treated with an antagonist of the BK-2 receptor, include, but are not limited to inflammatory pain, postoperative pain, and vaginal inflammation and pain. The invention further provides a method of treating patients suffering from hypertension with an amount of compound of the invention sufficient to reduce blood pressure. Selective antagonists of the BK-2 receptor are useful as anti-hypertensives.
In a further aspect the invention provide a method of treating a patient suffering from Type II (adult-onset) diabetes with an amount of a compound of the invention sufficient to alter the symptoms. Selective agonists of the BK-2 receptor are useful for treating type II diabetes. The invention also provides methods of treating patients suffering from circulatory or cardiovascular disorders with an amount of a compound of the invention, that is a selective agonist of the BK-2 receptor, sufficient to reduce the symptoms of the circulatory of cardiovascular disorder. Such circulatory or cardiovascular disorders include, but are not limited to heart failure, peripheral circulatory disorders, myocardial infarction, ostmyocardial infarction syndrome, angina pectoris, retinochoroidal circulatory disorders, nd myocardial ischemia. Selective agonists of the BK-2 stimulate NO release and as such re useful for treating climacteric disturbance and male infertility. The invention provides methods of treating patients suffering from such disorders with an amount of a compound of the invention sufficient to reduce the symptoms of disorder.
Bradykinin has been shown to increase the permeability of blood-brain barrier and blood-brain tumor barrier. The invention provides a method of increasing the brain concentration of a CNS active compounds which comprises administering a patient in need of such treatment a compound of the invention, that is a selective agonist of the BK-2 receptor, along with a CNS active compound, and thereby increasing the brain concentration of the CNS active compound. In a particularly preferred embodiment the invention provides a method of increasing the brain concentration of anti-cancer and anti-tumor agents which comprises administering a patient suffering from brain cancer or a brain tumor a compound of the invention, that is a selective agonist of the BK-2 receptor, along with a anti-cancer and anti-tumor agent, and thereby increasing the brain concentration of the anti-cancer or anti-tumor agent.
Patients include human and non-human animals, such as domestic pets and farm animals (for example, dogs, cats, swine, sheep, horses, cattle, etc.).
The present invention also pertains to methods of inhibiting the binding of bradykinin to the bradykinin receptors, especially BK-2 receptors which methods involve contacting a compound of the invention with cells expressing bradykinon receptors, (preferably BK-2 receptors) wherein the compound is present at a concentration sufficient to inhibit the binding of bradykinin to bradykinin receptors in vitro. This method includes inhibiting the binding of bradykinin to bradykinin receptors in vivo, e.g., in a patient given an amount of a compound of formula I or any of the subformulae thereof, that would be sufficient to inhibit the binding of bradykinon to BK-2 receptors in vitro. The amount of a compound that would be sufficient to inhibit the binding bradykinin to the BK-2 receptor may be readily determined via a BK-2 receptor binding assay, such as the assay described in Example 9. The BK-2 receptors used to determine in vitro binding may be obtained from a variety of sources, for example from preparations of rat brain or from cells expressing cloned human BK-2 receptors.
The present invention also pertains to methods for altering the signal-transducing activity of bradykinin receptors, said method comprising exposing cells expressing such receptors to an effective amount of a compound of the invention. This method includes altering the signal-transducing activity of BK-2 receptors in vivo, e.g., in a patient given an amount of a compound of formula I, or the subformulae thereof, that would be sufficient to alter the signal-transducing activity of BK-2 receptors in vitro. The amount of a compound that would be sufficient to alter the signal-transducing activity of bradykinin receptors may be determined via a bradykinin receptor signal transduction assay, such as the assay described in Example 10.
The bradykinin receptor ligands (i.e. the compounds of the invention) provided by this invention and labeled derivatives thereof are also useful as standards and reagents in determining the ability of a potential pharmaceutical to bind to the BK-2 receptor.
Isotopically-labeled compounds of this invention, which are identical to those recited in formula I, or the subformulae thereof, but for the fact that one or more atoms are replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number usually found in nature, are also useful for mapping the location of bradykinin receptors (e.g., in tissue sections via autoradiography) and as radiotracers for positron emission tomography (PET) imaging, single photon emission computerized tomography (SPECT), and the like, to characterize such receptors in living subjects. Examples of isotopes that can be incorporated into compounds of the invention include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorous, fluorine and chlorine, such as 2H, 3H, 11C, 13C, 14C, 15N, 18O, 17O, 31P, 32P, 35S, 18F, and 36Cl, respectively. Compounds of the present invention, prodrugs thereof, and pharmaceutically acceptable salts of said compounds or of said prodrugs which contain the aforementioned isotopes and/or other isotopes of other atoms are within the scope of this invention. In addition, substitution with heavy isotopes such as deuterium, i.e., 2H, can afford certain therapeutic advantages resulting from greater metabolic stability, for example increased in vivo half-life or reduced dosage requirements and, hence, may be preferred in some circumstances. Isotopically labeled compounds of formula Ia, or the subformulae thereof, of this invention and prodrugs thereof can generally be prepared by carrying out the procedures disclosed in the Schemes and/or in the examples below, by substituting a readily available isotopically labeled reagent for a non-isotopically labeled reagent.
The compounds of general Formula I may be administered orally, topically, parenterally, by inhalation or spray or rectally in dosage unit formulations containing conventional non-toxic pharmaceutically acceptable carriers, adjuvants and vehicles. The term parenteral as used herein includes percutaneous, subcutaneous, intravascular (e.g., intravenous), intramuscular, or intrathecal injection or infusion techniques and the like. In addition, there is provided a pharmaceutical formulation comprising a compound of general Formula I and a pharmaceutically acceptable carrier. One or more compounds of general Formula I may be present in association with one or more non-toxic pharmaceutically acceptable carriers and/or diluents and/or adjuvants and if desired other active ingredients. The pharmaceutical compositions containing compounds of general Formula I may be in a form suitable for oral use, for example, as tablets, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules, emulsion, hard or soft capsules, or syrups or elixirs.
Compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions and such compositions may contain one or more agents selected from the group consisting of sweetening agents, flavoring agents, coloring agents and preservative agents in order to provide pharmaceutically elegant and palatable preparations. Tablets contain the active ingredient in admixture with non-toxic pharmaceutically acceptable excipients that are suitable for the manufacture of tablets. These excipients may be for example, inert diluents, such as calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate; granulating and disintegrating agents, for example, corn starch, or alginic acid; binding agents, for example starch, gelatin or acacia, and lubricating agents, for example magnesium stearate, stearic acid or talc. The tablets may be uncoated or they may be coated by known techniques. In some cases such coatings may be prepared by known techniques so as to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period. For example, a time delay material such as glyceryl monosterate or glyceryl distearate may be employed.
Formulations for oral use may also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, for example, calcium carbonate, calcium phosphate or kaolin, or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example peanut oil, liquid paraffin or olive oil.
Aqueous suspensions contain the active materials in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients are suspending agents, for example sodium carboxymethylcellulose, methylcellulose, hydropropylmethylcellulose, sodium alginate, polyvinylpyrrolidone, gum tragacanth and gum acacia; dispersing or wetting agents may be a naturally-occurring phosphatide, for example, lecithin, or condensation products of an alkylene oxide with fatty acids, for example polyoxyethylene stearate, or condensation products of ethylene oxide with long chain aliphatic alcohols, for example heptadecaethyleneoxycetanol, or condensation products of ethylene oxide with partial esters derived from fatty acids and a hexitol such as polyoxyethylene sorbitol monooleate, or condensation products of ethylene oxide with partial esters derived from fatty acids and hexitol anhydrides, for example polyethylene sorbitan monooleate. The aqueous suspensions may also contain one or more preservatives, for example ethyl, or n-propyl p-hydroxybenzoate, one or more coloring agents, one or more flavoring agents, and one or more sweetening agents, such as sucrose or saccharin.
Oily suspensions may be formulated by suspending the active ingredients in a vegetable oil, for example arachis oil, olive oil, sesame oil or coconut oil, or in a mineral oil such as liquid paraffin. The oily suspensions may contain a thickening agent, for example beeswax, hard paraffin or cetyl alcohol. Sweetening agents and flavoring agents may be added to provide palatable oral preparations. These compositions may be preserved by the addition of an anti-oxidant such as ascorbic acid.
Dispersible powders and granules suitable for preparation of an aqueous suspension by the addition of water provide the active ingredient in admixture with a dispersing or wetting agent, suspending agent and one or more preservatives. Suitable dispersing or wetting agents and suspending agents are exemplified by those already mentioned above. Additional excipients, for example sweetening, flavoring and coloring agents, may also be present.
Pharmaceutical compositions of the invention may also be in the form of oil-in-water emulsions. The oily phase may be a vegetable oil or a mineral oil or mixtures of these. Suitable emulsifying agents may be naturally-occurring gums, for example gum acacia or gum tragacanth, naturally-occurring phosphatides, for example soy bean, lecithin, and esters or partial esters derived from fatty acids and hexitol, anhydrides, for example sorbitan monoleate, and condensation products of the said partial esters with ethylene oxide, for example polyoxyethylene sorbitan monoleate. The emulsions may also contain sweetening and flavoring agents.
Syrups and elixirs may be formulated with sweetening agents, for example, glycerol, propylene glycol, sorbitol, glucose or sucrose. Such formulations may also contain a demulcent, a preservative and flavoring and coloring agents. The pharmaceutical compositions may be in the form of a sterile injectable aqueous or oleaginous suspension. This suspension may be formulated according to the known art using those suitable dispersing or wetting agents and suspending agents that have been mentioned above. The sterile injectable preparation may also be sterile injectable solution or suspension in a non-toxic parentally acceptable diluent or solvent, for example as a solution in 1,3-butanediol. Among the acceptable vehicles and solvents that may be employed are water, Ringer""s solution and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed including synthetic mono-or diglycerides. In addition, fatty acids such as oleic acid find use in the preparation of injectables.
The compounds of general Formula I may also be administered in the form of suppositories, e.g., for rectal administration of the drug. These compositions can be prepared by mixing the drug with a suitable non-irritating excipient that is solid at ordinary temperatures but liquid at the rectal temperature and will therefore melt in the rectum to release the drug. Such materials are cocoa butter and polyethylene glycols.
Compounds of general Formula I may be administered parenterally in a sterile medium. The drug, depending on the vehicle and concentration used, can either be suspended or dissolved in the vehicle. Advantageously, adjuvants such as local anesthetics, preservatives and buffering agents can be dissolved in the vehicle.
Dosage levels of the order of from about 0.1 mg to about 140 mg per kilogram of body weight per day are useful in the treatment of the above-indicated conditions (about 0.5 mg to about 7 g per patient per day). The amount of active ingredient that may be combined with the carrier materials to produce a single dosage form will vary depending upon the host treated and the particular mode of administration. Dosage unit forms will generally contain between from about 1 mg to about 500 mg of an active ingredient.
It will be understood, however, that the specific dose level for any particular patient will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, general health, sex, diet, time of administration, route of administration, and rate of excretion, drug combination and the severity of the particular disease undergoing therapy.
Preferred compounds of the invention will have certain pharmacological properties. Such properties include, but are not limited to oral bioavailability, low toxicity, low serum protein binding and desirable in vitro and in vivo half-lives. Penetration of the blood brain barrier for compounds used to treat CNS disorders is necessary, while low brain levels of compounds used to treat peripheral disorders are often preferred.
Assays may be used to predict these desirable pharmacological properties. Assays used to predict bioavailability include transport across human intestinal cell monolayers, including Caco-2 cell monolayers. Toxicity to cultured hepatocytes may be used to predict compound toxicity. Penetration of the blood brain barrier of a compound in humans may be predicted from the brain levels of the compound in laboratory animals given the compound intravenously.
Serum protein binding may be predicted from albumin binding assays. Such assays are described in a review by Oravcova, et al. (Journal of Chromatography B 1996, 677, 1-27).
Compound half-life is inversely proportional to the frequency of dosage of a compound. In vitro half-lives of compounds may be predicted from assays of microsomal half-life as described by Kuhnz and Gieschen (Drug Metabolism and Disposition 1998, 26, 1120-1127).
As discussed above, preferred compounds of the invention exhibit good activity in in vitro Bradykinin receptor binding assays, especially BK-2 receptor binding assays, and specifically the assay as specified in Example 9, which follows. References herein to xe2x80x9cin vitro BK-2 receptor binding assayxe2x80x9d are intended to refer to that protocol as defined in Example 9 which follows.
For administration to non-human animals, the composition may also be added to the animal feed or drinking water. It will be convenient to formulate these animal feed and drinking water compositions so that the animal takes in an appropriate quantity of the composition along with its diet. It will also be convenient to present the composition as a premix for addition to the feed or drinking water.
The disclosures of all articles and references mentioned in this application, including patents, are incorporated herein by reference.